351
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Khorsandi SE, Taanman JW, Heaton N. Subunit composition of respiratory chain complex 1 and its responses to oxygen in mitochondria from human donor livers. BMC Res Notes 2017; 10:547. [PMID: 29096719 PMCID: PMC5667463 DOI: 10.1186/s13104-017-2863-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/24/2017] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Donor liver function in transplantation is defined by mitochondrial function and the ability of mitochondria to recover from the sequence of warm and/or cold ischemia. Mitochondrial resilience maybe related to assembly and- subunit composition of Complex 1. The aim of this study was to determine if Complex 1 subunit composition was different in donor livers of varying quality and whether oxygen exposure had any effect. RESULTS Five human livers not suitable for transplant were split. One half placed in cold static storage and the other half exposed to 40% oxygen for 2 h. Protein was extracted for western blot. Membranes were probed with antibodies against β-actin and the following subunits of Complex 1: MTND1, NDUFA10, NDUFB6 and NDUFV2. No difference in steady state Complex 1 subunit composition was demonstrated between donor livers of varying quality, in terms of steatosis or mode of donation. Neither did exposure to oxygen influence Complex 1 subunit composition. This small observational study on subunit levels suggest that Complex 1 is fully assembled as no degradation of subunits associated with the different parts of the enzyme was seen.
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Affiliation(s)
- S E Khorsandi
- Institute of Liver Studies, King's College Hospital, Kings College London, London, SE5 9RS, UK
| | - J W Taanman
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London, UK
| | - N Heaton
- Institute of Liver Studies, King's College Hospital, Kings College London, London, SE5 9RS, UK.
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352
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Massoz S, Hanikenne M, Bailleul B, Coosemans N, Radoux M, Miranda-Astudillo H, Cardol P, Larosa V, Remacle C. In vivo chlorophyll fluorescence screening allows the isolation of a Chlamydomonas mutant defective for NDUFAF3, an assembly factor involved in mitochondrial complex I assembly. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:584-595. [PMID: 28857403 DOI: 10.1111/tpj.13677] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 08/11/2017] [Accepted: 08/21/2017] [Indexed: 05/16/2023]
Abstract
The qualitative screening method used to select complex I mutants in the microalga Chlamydomonas, based on reduced growth under heterotrophic conditions, is not suitable for high-throughput screening. In order to develop a fast screening method based on measurements of chlorophyll fluorescence, we first demonstrated that complex I mutants displayed decreased photosystem II efficiency in the genetic background of a photosynthetic mutation leading to reduced formation of the electrochemical proton gradient in the chloroplast (pgrl1 mutation). In contrast, single mutants (complex I and pgrl1 mutants) could not be distinguished from the wild type by their photosystem II efficiency under the conditions tested. We next performed insertional mutagenesis on the pgrl1 mutant. Out of about 3000 hygromycin-resistant insertional transformants, 46 had decreased photosystem II efficiency and three were complex I mutants. One of the mutants was tagged and whole genome sequencing identified the resistance cassette in NDUFAF3, a homolog of the human NDUFAF3 gene, encoding for an assembly factor involved in complex I assembly. Complemented strains showed restored complex I activity and assembly. Overall, we describe here a screening method which is fast and particularly suited for the identification of Chlamydomonas complex I mutants.
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Affiliation(s)
- Simon Massoz
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Marc Hanikenne
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- InBioS - Functional Genomics and Plant Molecular Imaging, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Benjamin Bailleul
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Nadine Coosemans
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Michèle Radoux
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Hector Miranda-Astudillo
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Pierre Cardol
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Véronique Larosa
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Claire Remacle
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
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353
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Gamiz-Hernandez AP, Jussupow A, Johansson MP, Kaila VRI. Terminal Electron-Proton Transfer Dynamics in the Quinone Reduction of Respiratory Complex I. J Am Chem Soc 2017; 139:16282-16288. [PMID: 29017321 PMCID: PMC6300313 DOI: 10.1021/jacs.7b08486] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Complex I functions as a redox-driven proton pump in aerobic respiratory chains. By reducing quinone (Q), complex I employs the free energy released in the process to thermodynamically drive proton pumping across its membrane domain. The initial Q reduction step plays a central role in activating the proton pumping machinery. In order to probe the energetics, dynamics, and molecular mechanism for the proton-coupled electron transfer process linked to the Q reduction, we employ here multiscale quantum and classical molecular simulations. We identify that both ubiquinone (UQ) and menaquinone (MQ) can form stacking and hydrogen-bonded interactions with the conserved Q-binding-site residue His-38 and that conformational changes between these binding modes modulate the Q redox potentials and the rate of electron transfer (eT) from the terminal N2 iron-sulfur center. We further observe that, while the transient formation of semiquinone is not proton-coupled, the second eT process couples to a semiconcerted proton uptake from conserved tyrosine (Tyr-87) and histidine (His-38) residues within the active site. Our calculations indicate that both UQ and MQ have low redox potentials around -260 and -230 mV, respectively, in the Q-binding site, respectively, suggesting that release of the Q toward the membrane is coupled to an energy transduction step that could thermodynamically drive proton pumping in complex I.
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Affiliation(s)
- Ana P Gamiz-Hernandez
- Department Chemie, Technische Universität München (TUM) , Lichtenbergstraße 4, Garching D-85747, Germany
| | - Alexander Jussupow
- Department Chemie, Technische Universität München (TUM) , Lichtenbergstraße 4, Garching D-85747, Germany
| | - Mikael P Johansson
- Department Chemie, Technische Universität München (TUM) , Lichtenbergstraße 4, Garching D-85747, Germany.,Department of Chemistry, University of Helsinki , P.O. Box 55, Helsinki FI-00014, Finland
| | - Ville R I Kaila
- Department Chemie, Technische Universität München (TUM) , Lichtenbergstraße 4, Garching D-85747, Germany
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354
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Kitazoe Y, Hasegawa M, Tanaka M, Futami M, Futami J. Mitochondrial determinants of mammalian longevity. Open Biol 2017; 7:rsob.170083. [PMID: 29070610 PMCID: PMC5666079 DOI: 10.1098/rsob.170083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 09/30/2017] [Indexed: 12/18/2022] Open
Abstract
Current ageing theories are far from satisfactory because of the many determinants involved in ageing. The well-known rate-of-living theory assumes that the product (lifetime energy expenditure, LEE) of maximum lifespan (MLS) and mass-specific basal metabolic rate (msBMR) is approximately constant. Although this theory provides a significant inverse correlation between msBMR and MLS as a whole for mammals, it remains problematic for two reasons. First, several interspecies studies within respective orders (typically within rodents) have shown no inverse relationships between msBMR and MLS. Second, LEE values widely vary in mammals and birds. Here, to solve these two problems, we introduced a new quantity designated as mitochondrial (mt) lifetime energy output, mtLEO = MLS × mtMR, in place of LEE, by using the mt metabolic rate (mtMR) per mitochondrion. Thereby, we found that mtLEO values were distributed more narrowly than LEE ones, and strongly correlated with the four amino-acid variables (AAVs) of Ser, Thr and Cys contents and hydrophobicity of mtDNA-encoded membrane proteins (these variables were related to the stability of these proteins). Consequently, only these two mt items, mtMR and the AAVs, solved the above-mentioned problems in the rate-of-living theory, and thus extensively improved the correlation with MLS compared with that given by LEE.
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Affiliation(s)
- Yasuhiro Kitazoe
- Center of Medical Information Science, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
| | - Masami Hasegawa
- Institute of Statistical Mathematics, Midori-cho 10-3, Tachikawa, Tokyo 190-8562, Japan
| | - Masashi Tanaka
- Department of Genomics for Longevity and Health, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi, Tokyo 173-0015, Japan
| | - Midori Futami
- Department of Biomedical Engineering, Faculty of Engineering, Okayama University of Science, 1-1 Ridaicho, Okayama 700-0005, Japan
| | - Junichiro Futami
- Department of Biotechnology, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
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355
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Letts JA, Sazanov LA. Clarifying the supercomplex: the higher-order organization of the mitochondrial electron transport chain. Nat Struct Mol Biol 2017; 24:800-808. [PMID: 28981073 DOI: 10.1038/nsmb.3460] [Citation(s) in RCA: 220] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 08/03/2017] [Indexed: 12/27/2022]
Abstract
The oxidative phosphorylation electron transport chain (OXPHOS-ETC) of the inner mitochondrial membrane is composed of five large protein complexes, named CI-CV. These complexes convert energy from the food we eat into ATP, a small molecule used to power a multitude of essential reactions throughout the cell. OXPHOS-ETC complexes are organized into supercomplexes (SCs) of defined stoichiometry: CI forms a supercomplex with CIII2 and CIV (SC I+III2+IV, known as the respirasome), as well as with CIII2 alone (SC I+III2). CIII2 forms a supercomplex with CIV (SC III2+IV) and CV forms dimers (CV2). Recent cryo-EM studies have revealed the structures of SC I+III2+IV and SC I+III2. Furthermore, recent work has shed light on the assembly and function of the SCs. Here we review and compare these recent studies and discuss how they have advanced our understanding of mitochondrial electron transport.
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Affiliation(s)
- James A Letts
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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356
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Belevich N, von Ballmoos C, Verkhovskaya M. Activation of Proton Translocation by Respiratory Complex I. Biochemistry 2017; 56:5691-5697. [PMID: 28960069 DOI: 10.1021/acs.biochem.7b00727] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Activation of proton pumping by reconstituted and native membrane-bound Complex I was studied using optical electric potential- and pH-sensitive probes. We find that reconstituted Complex I has a delay in proton translocation, which is significantly longer than the delay in quinone reductase activity, indicating an initially decoupled state of Complex I. Studies of the amount of NADH required for the activation of pumping indicate the prerequisite of multiple turnovers. Proton pumping by Complex I was also activated by NADPH, excluding significant reduction of Complex I and a preexisting Δψ as activation factors. Co-reconstitution of Complex I and ATPase did not indicate an increased membrane permeability for protons in the uncoupled Complex I state. The delay in Complex I proton pumping activation was also observed in subbacterial vesicles. While it is negligible at room temperature, it strongly increases at a lower temperature. We conclude that Complex I undergoes a conversion from a decoupled state to a coupled state upon activation. The possible origins and importance of the observed phenomenon are discussed.
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Affiliation(s)
- Nikolai Belevich
- Institute of Biotechnology, University of Helsinki , P.O. Box 65, Viikinkaari 1, FIN-00014 Helsinki, Finland
| | - Christoph von Ballmoos
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Marina Verkhovskaya
- Institute of Biotechnology, University of Helsinki , P.O. Box 65, Viikinkaari 1, FIN-00014 Helsinki, Finland
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357
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Di Meo I, Marchet S, Lamperti C, Zeviani M, Viscomi C. AAV9-based gene therapy partially ameliorates the clinical phenotype of a mouse model of Leigh syndrome. Gene Ther 2017; 24:661-667. [PMID: 28753212 PMCID: PMC5658670 DOI: 10.1038/gt.2017.53] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/18/2017] [Accepted: 06/13/2017] [Indexed: 02/02/2023]
Abstract
Leigh syndrome (LS) is the most common infantile mitochondrial encephalopathy. No treatment is currently available for this condition. Mice lacking Ndufs4, encoding NADH: ubiquinone oxidoreductase iron-sulfur protein 4 (NDUFS4) recapitulates the main findings of complex I (cI)-related LS, including severe multisystemic cI deficiency and progressive neurodegeneration. In order to develop a gene therapy approach for LS, we used here an AAV2/9 vector carrying the human NDUFS4 coding sequence (hNDUFS4). We administered AAV2/9-hNDUFS4 by intravenous (IV) and/or intracerebroventricular (ICV) routes to either newborn or young Ndufs4-/- mice. We found that IV administration alone was only able to correct the cI deficiency in peripheral organs, whereas ICV administration partially corrected the deficiency in the brain. However, both treatments failed to improve the clinical phenotype or to prolong the lifespan of Ndufs4-/- mice. In contrast, combined IV and ICV treatments resulted, along with increased cI activity, in the amelioration of the rotarod performance and in a significant prolongation of the lifespan. Our results indicate that extraneurological organs have an important role in LS pathogenesis and provide an insight into current limitations of adeno-associated virus (AAV)-mediated gene therapy in multisystem disorders. These findings warrant future investigations to develop new vectors able to efficiently target multiple organs.
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Affiliation(s)
- I Di Meo
- IRCCS Foundation Neurological Institute ‘C. Besta’, Milan, Italy
| | - S Marchet
- IRCCS Foundation Neurological Institute ‘C. Besta’, Milan, Italy
| | - C Lamperti
- IRCCS Foundation Neurological Institute ‘C. Besta’, Milan, Italy
| | - M Zeviani
- University of Cambridge/Medical Research Council, Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
| | - C Viscomi
- University of Cambridge/Medical Research Council, Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
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358
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Structure and electrochemistry of proteins harboring iron-sulfur clusters of different nuclearities. Part I. [4Fe-4S] + [2Fe-2S] iron-sulfur proteins. J Struct Biol 2017; 200:1-19. [DOI: 10.1016/j.jsb.2017.05.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/25/2017] [Indexed: 01/08/2023]
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359
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360
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Stochastic resonance in a proton pumping Complex I of mitochondria membranes. Sci Rep 2017; 7:12405. [PMID: 28963519 PMCID: PMC5622088 DOI: 10.1038/s41598-017-12746-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 09/15/2017] [Indexed: 11/24/2022] Open
Abstract
We make use of the physical mechanism of proton pumping in the so-called Complex I within mitochondria membranes. Our model is based on sequential charge transfer assisted by conformational changes which facilitate the indirect electron-proton coupling. The equations of motion for the proton operators are derived and solved numerically in combination with the phenomenological Langevin equation describing the periodic conformational changes. We show that with an appropriate set of parameters, protons can be transferred against an applied voltage. In addition, we demonstrate that only the joint action of the periodic energy modulation and thermal noise leads to efficient uphill proton transfer, being a manifestation of stochastic resonance.
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361
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Structures of the human mitochondrial ribosome in native states of assembly. Nat Struct Mol Biol 2017; 24:866-869. [PMID: 28892042 DOI: 10.1038/nsmb.3464] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 08/15/2017] [Indexed: 12/11/2022]
Abstract
Mammalian mitochondrial ribosomes (mitoribosomes) have less rRNA content and 36 additional proteins compared with the evolutionarily related bacterial ribosome. These differences make the assembly of mitoribosomes more complex than the assembly of bacterial ribosomes, but the molecular details of mitoribosomal biogenesis remain elusive. Here, we report the structures of two late-stage assembly intermediates of the human mitoribosomal large subunit (mt-LSU) isolated from a native pool within a human cell line and solved by cryo-EM to ∼3-Å resolution. Comparison of the structures reveals insights into the timing of rRNA folding and protein incorporation during the final steps of ribosomal maturation and the evolutionary adaptations that are required to preserve biogenesis after the structural diversification of mitoribosomes. Furthermore, the structures redefine the ribosome silencing factor (RsfS) family as multifunctional biogenesis factors and identify two new assembly factors (L0R8F8 and mt-ACP) not previously implicated in mitoribosomal biogenesis.
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362
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Senkler J, Senkler M, Braun HP. Structure and function of complex I in animals and plants - a comparative view. PHYSIOLOGIA PLANTARUM 2017; 161:6-15. [PMID: 28261805 DOI: 10.1111/ppl.12561] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/03/2017] [Accepted: 02/06/2017] [Indexed: 06/06/2023]
Abstract
The mitochondrial NADH dehydrogenase complex (complex I) has a molecular mass of about 1000 kDa and includes 40-50 subunits in animals, fungi and plants. It is composed of a membrane arm and a peripheral arm and has a conserved L-like shape in all species investigated. However, in plants and possibly some protists it has a second peripheral domain which is attached to the membrane arm on its matrix exposed side at a central position. The extra domain includes proteins resembling prokaryotic gamma-type carbonic anhydrases. We here present a detailed comparison of complex I from mammals and flowering plants. Forty homologous subunits are present in complex I of both groups of species. In addition, five subunits are present in mammalian complex I, which are absent in plants, and eight to nine subunits are present in plant complex I which do not occur in mammals. Based on the atomic structure of mammalian complex I and biochemical insights into complex I architecture from plants we mapped the species-specific subunits. Interestingly, four of the five animal-specific and five of the eight to nine plant-specific subunits are localized at the inner surface of the membrane arm of complex I in close proximity. We propose that the inner surface of the membrane arm represents a workbench for attaching proteins to complex I, which are not directly related to respiratory electron transport, like nucleoside kinases, acyl-carrier proteins or carbonic anhydrases. We speculate that further enzyme activities might be bound to this micro-location in other groups of organisms.
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Affiliation(s)
- Jennifer Senkler
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Michael Senkler
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Hans-Peter Braun
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany
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363
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Pinegin B, Vorobjeva N, Pashenkov M, Chernyak B. The role of mitochondrial ROS in antibacterial immunity. J Cell Physiol 2017; 233:3745-3754. [PMID: 28771715 DOI: 10.1002/jcp.26117] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 08/01/2017] [Indexed: 12/26/2022]
Abstract
Reactive oxygen species (ROS) are essential participants of various innate immune cell responses against microorganisms and are also involved in many cellular regulatory pathways. It was believed that the main pool of ROS in the innate immune cells is generated by the NADPH oxidase enzymatic complex. However, it was discovered recently that mitochondrial ROS (mtROS) are equally important for the functioning of the immune system. mtROS play an important role in the development of the antimicrobial innate immune responses. The present mini-review summarizes the most recent data on the role of mtROS in the antibacterial immunity. The principles of mtROS formation and possible mechanisms of their generation under the activation of innate immunity are highlighted in this review. We also speculate on the possibilities of using activators of mtROS production in clinical practice.
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Affiliation(s)
- Boris Pinegin
- Laboratory of Clinical Immunology, National Research Center "Institute of Immunology" of the Federal Medical-Biological Agency, Moscow, Russia
| | - Nina Vorobjeva
- Department of Immunology, Biological Faculty, Lomonosov Moscow State University, Moscow, Russia
| | - Mikhail Pashenkov
- Laboratory of Clinical Immunology, National Research Center "Institute of Immunology" of the Federal Medical-Biological Agency, Moscow, Russia
| | - Boris Chernyak
- Department of Bioenergetics, A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
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364
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Guo R, Zong S, Wu M, Gu J, Yang M. Architecture of Human Mitochondrial Respiratory Megacomplex I 2III 2IV 2. Cell 2017; 170:1247-1257.e12. [PMID: 28844695 DOI: 10.1016/j.cell.2017.07.050] [Citation(s) in RCA: 322] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 06/20/2017] [Accepted: 07/28/2017] [Indexed: 01/01/2023]
Abstract
The respiratory megacomplex represents the highest-order assembly of respiratory chain complexes, and it allows mitochondria to respond to energy-requiring conditions. To understand its architecture, we examined the human respiratory chain megacomplex-I2III2IV2 (MCI2III2IV2) with 140 subunits and a subset of associated cofactors using cryo-electron microscopy. The MCI2III2IV2 forms a circular structure with the dimeric CIII located in the center, where it is surrounded by two copies each of CI and CIV. Two cytochrome c (Cyt.c) molecules are positioned to accept electrons on the surface of the c1 state CIII dimer. Analyses indicate that CII could insert into the gaps between CI and CIV to form a closed ring, which we termed the electron transport chain supercomplex. The structure not only reveals the precise assignment of individual subunits of human CI and CIII, but also enables future in-depth analysis of the electron transport chain as a whole.
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Affiliation(s)
- Runyu Guo
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Shuai Zong
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Meng Wu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Jinke Gu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Maojun Yang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China.
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365
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Musatov A, Sedlák E. Role of cardiolipin in stability of integral membrane proteins. Biochimie 2017; 142:102-111. [PMID: 28842204 DOI: 10.1016/j.biochi.2017.08.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 08/21/2017] [Indexed: 01/13/2023]
Abstract
Cardiolipin (CL) is a unique phospholipid with a dimeric structure having four acyl chains and two phosphate groups found almost exclusively in certain membranes of bacteria and of mitochondria of eukaryotes. CL interacts with numerous proteins and has been implicated in function and stabilization of several integral membrane proteins (IMPs). While both functional and stabilization roles of CL in IMPs has been generally acknowledged, there are, in fact, only limited number of quantitative analysis that support this function of CL. This is likely caused by relatively complex determination of parameters characterizing stability of IMPs and particularly intricate assessment of role of specific phospholipids such as CL in IMPs stability. This review aims to summarize quantitative findings regarding stabilization role of CL in IMPs reported up to now.
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Affiliation(s)
- Andrej Musatov
- Department of Biophysics, Institute of Experimental Physics Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovakia.
| | - Erik Sedlák
- Centre for Interdisciplinary Biosciences, P.J. Šafárik University, Jesenná 5, 040 01 Košice, Slovakia.
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366
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Reduction of the off-pathway iron-sulphur cluster N1a of Escherichia coli respiratory complex I restrains NAD + dissociation. Sci Rep 2017; 7:8754. [PMID: 28821859 PMCID: PMC5562879 DOI: 10.1038/s41598-017-09345-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/25/2017] [Indexed: 12/24/2022] Open
Abstract
Respiratory complex I couples the electron transfer from NADH to ubiquinone with the translocation of protons across the membrane. The reaction starts with NADH oxidation by a flavin cofactor followed by transferring the electrons through a chain of seven iron-sulphur clusters to quinone. An eighth cluster called N1a is located proximally to flavin, but on the opposite side of the chain of clusters. N1a is strictly conserved although not involved in the direct electron transfer to quinone. Here, we show that the NADH:ferricyanide oxidoreductase activity of E. coli complex I is strongly diminished when the reaction is initiated by an addition of ferricyanide instead of NADH. This effect is significantly less pronounced in a variant containing N1a with a 100 mV more negative redox potential. Detailed kinetic analysis revealed that the reduced activity is due to a lower dissociation constant of bound NAD+. Thus, reduction of N1a induces local structural rearrangements of the protein that stabilise binding of NAD+. The variant features a considerably enhanced production of reactive oxygen species indicating that bound NAD+ represses this process.
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367
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Haapanen O, Sharma V. Role of water and protein dynamics in proton pumping by respiratory complex I. Sci Rep 2017; 7:7747. [PMID: 28798393 PMCID: PMC5552823 DOI: 10.1038/s41598-017-07930-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/05/2017] [Indexed: 11/29/2022] Open
Abstract
Membrane bound respiratory complex I is the key enzyme in the respiratory chains of bacteria and mitochondria, and couples the reduction of quinone to the pumping of protons across the membrane. Recently solved crystal or electron microscopy structures of bacterial and mitochondrial complexes have provided significant insights into the electron and proton transfer pathways. However, due to large spatial separation between the electron and proton transfer routes, the molecular mechanism of coupling remains unclear. Here, based on atomistic molecular dynamics simulations performed on the entire structure of complex I from Thermus thermophilus, we studied the hydration of the quinone-binding site and the membrane-bound subunits. The data from simulations show rapid diffusion of water molecules in the protein interior, and formation of hydrated regions in the three antiporter-type subunits. An unexpected water-protein based connectivity between the middle of the Q-tunnel and the fourth proton channel is also observed. The protonation-state dependent dynamics of key acidic residues in the Nqo8 subunit suggest that the latter may be linked to redox-coupled proton pumping in complex I. We propose that in complex I the proton and electron transfer paths are not entirely separate, instead the nature of coupling may in part be ‘direct’.
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Affiliation(s)
- Outi Haapanen
- Department of Physics, University of Helsinki, P. O. Box 64, FI-00014, Helsinki, Finland.,Department of Physics, Tampere University of Technology, P. O. Box 692, FI-33101, Tampere, Finland
| | - Vivek Sharma
- Department of Physics, University of Helsinki, P. O. Box 64, FI-00014, Helsinki, Finland. .,Department of Physics, Tampere University of Technology, P. O. Box 692, FI-33101, Tampere, Finland. .,Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
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368
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Angerer H, Schönborn S, Gorka J, Bahr U, Karas M, Wittig I, Heidler J, Hoffmann J, Morgner N, Zickermann V. Acyl modification and binding of mitochondrial ACP to multiprotein complexes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1913-1920. [PMID: 28802701 DOI: 10.1016/j.bbamcr.2017.08.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 08/03/2017] [Accepted: 08/08/2017] [Indexed: 01/06/2023]
Abstract
The mitochondrial acyl carrier protein (ACPM/NDUFAB1) is a central element of the mitochondrial fatty acid synthesis type II machinery. Originally ACPM was detected as a subunit of respiratory complex I but the reason for the association with the large enzyme complex remained elusive. Complex I from the aerobic yeast Yarrowia lipolytica comprises two different ACPMs, ACPM1 and ACPM2. They are anchored to the protein complex by LYR (leucine-tyrosine-arginine) motif containing protein (LYRM) subunits LYRM3 (NDUFB9) and LYRM6 (NDUFA6). The ACPM1-LYRM6 and ACPM2-LYRM3 modules are essential for complex I activity and assembly/stability, respectively. We show that in addition to the complex I bound fraction, ACPM1 is present as a free matrix protein and in complex with the soluble LYRM4(ISD11)/NFS1 complex implicated in Fe-S cluster biogenesis. We show that the presence of a long acyl chain bound to the phosphopantetheine cofactor is important for docking ACPMs to protein complexes and we propose that association of ACPMs and LYRMs is universally based on a new protein-protein interaction motif.
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Affiliation(s)
- Heike Angerer
- Goethe University Frankfurt, Medical School, Institute of Biochemistry II, Structural Bioenergetics Group, Max-von-Laue Str. 9, 60438 Frankfurt, Germany.
| | - Stefan Schönborn
- Goethe University Frankfurt, Institute of Pharmaceutical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Jan Gorka
- Goethe University Frankfurt, Institute of Pharmaceutical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Ute Bahr
- Goethe University Frankfurt, Institute of Pharmaceutical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Michael Karas
- Goethe University Frankfurt, Institute of Pharmaceutical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Ilka Wittig
- Functional Proteomics, SFB 815 core unit, Goethe-University Frankfurt, Medical School, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Juliana Heidler
- Functional Proteomics, SFB 815 core unit, Goethe-University Frankfurt, Medical School, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Jan Hoffmann
- Goethe University Frankfurt, Institute of Physical and Theoretical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Nina Morgner
- Goethe University Frankfurt, Institute of Physical and Theoretical Chemistry, Max-von-Laue Str. 9, 60438 Frankfurt, Germany
| | - Volker Zickermann
- Goethe University Frankfurt, Medical School, Institute of Biochemistry II, Structural Bioenergetics Group, Max-von-Laue Str. 9, 60438 Frankfurt, Germany; Cluster of Excellence Macromolecular Complexes, Goethe University Frankfurt, Germany.
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369
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Structural insights into the alternative oxidases: are all oxidases made equal? Biochem Soc Trans 2017; 45:731-740. [PMID: 28620034 DOI: 10.1042/bst20160178] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/08/2017] [Accepted: 03/10/2017] [Indexed: 01/15/2023]
Abstract
The alternative oxidases (AOXs) are ubiquinol-oxidoreductases that are members of the diiron carboxylate superfamily. They are not only ubiquitously distributed within the plant kingdom but also found in increasing numbers within the fungal, protist, animal and prokaryotic kingdoms. Although functions of AOXs are highly diverse in general, they tend to play key roles in thermogenesis, stress tolerance (through the management of radical oxygen species) and the maintenance of mitochondrial and cellular energy homeostasis. The best structurally characterised AOX is from Trypanosoma brucei In this review, we compare the structure of AOXs, created using homology modelling, from many important species in an attempt to explain differences in activity and sensitivity to AOX inhibitors. We discuss the implications of these findings not only for future structure-based drug design but also for the design of novel AOXs for gene therapy.
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370
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Abstract
The biogenesis of iron-sulfur (Fe/S) proteins in eukaryotes is a multistage, multicompartment process that is essential for a broad range of cellular functions, including genome maintenance, protein translation, energy conversion, and the antiviral response. Genetic and cell biological studies over almost 2 decades have revealed some 30 proteins involved in the synthesis of cellular [2Fe-2S] and [4Fe-4S] clusters and their incorporation into numerous apoproteins. Mechanistic aspects of Fe/S protein biogenesis continue to be elucidated by biochemical and ultrastructural investigations. Here, we review recent developments in the pursuit of constructing a comprehensive model of Fe/S protein assembly in the mitochondrion.
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Affiliation(s)
- Joseph J Braymer
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Robert-Koch-Strasse 6, 35032 Marburg
| | - Roland Lill
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Robert-Koch-Strasse 6, 35032 Marburg; LOEWE Zentrum für Synthetische Mikrobiologie SynMikro, Hans-Meerwein-Strasse, 35043 Marburg, Germany.
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371
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Lake NJ, Webb BD, Stroud DA, Richman TR, Ruzzenente B, Compton AG, Mountford HS, Pulman J, Zangarelli C, Rio M, Boddaert N, Assouline Z, Sherpa MD, Schadt EE, Houten SM, Byrnes J, McCormick EM, Zolkipli-Cunningham Z, Haude K, Zhang Z, Retterer K, Bai R, Calvo SE, Mootha VK, Christodoulou J, Rötig A, Filipovska A, Cristian I, Falk MJ, Metodiev MD, Thorburn DR. Biallelic Mutations in MRPS34 Lead to Instability of the Small Mitoribosomal Subunit and Leigh Syndrome. Am J Hum Genet 2017; 101:239-254. [PMID: 28777931 DOI: 10.1016/j.ajhg.2017.07.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 07/09/2017] [Indexed: 12/30/2022] Open
Abstract
The synthesis of all 13 mitochondrial DNA (mtDNA)-encoded protein subunits of the human oxidative phosphorylation (OXPHOS) system is carried out by mitochondrial ribosomes (mitoribosomes). Defects in the stability of mitoribosomal proteins or mitoribosome assembly impair mitochondrial protein translation, causing combined OXPHOS enzyme deficiency and clinical disease. Here we report four autosomal-recessive pathogenic mutations in the gene encoding the small mitoribosomal subunit protein, MRPS34, in six subjects from four unrelated families with Leigh syndrome and combined OXPHOS defects. Whole-exome sequencing was used to independently identify all variants. Two splice-site mutations were identified, including homozygous c.321+1G>T in a subject of Italian ancestry and homozygous c.322-10G>A in affected sibling pairs from two unrelated families of Puerto Rican descent. In addition, compound heterozygous MRPS34 mutations were identified in a proband of French ancestry; a missense (c.37G>A [p.Glu13Lys]) and a nonsense (c.94C>T [p.Gln32∗]) variant. We demonstrated that these mutations reduce MRPS34 protein levels and the synthesis of OXPHOS subunits encoded by mtDNA. Examination of the mitoribosome profile and quantitative proteomics showed that the mitochondrial translation defect was caused by destabilization of the small mitoribosomal subunit and impaired monosome assembly. Lentiviral-mediated expression of wild-type MRPS34 rescued the defect in mitochondrial translation observed in skin fibroblasts from affected subjects, confirming the pathogenicity of MRPS34 mutations. Our data establish that MRPS34 is required for normal function of the mitoribosome in humans and furthermore demonstrate the power of quantitative proteomic analysis to identify signatures of defects in specific cellular pathways in fibroblasts from subjects with inherited disease.
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372
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Masuya T, Murai M, Ito T, Aburaya S, Aoki W, Miyoshi H. Pinpoint Chemical Modification of the Quinone-Access Channel of Mitochondrial Complex I via a Two-Step Conjugation Reaction. Biochemistry 2017; 56:4279-4287. [DOI: 10.1021/acs.biochem.7b00612] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Takahiro Masuya
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Masatoshi Murai
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Takeshi Ito
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Shunsuke Aburaya
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Wataru Aoki
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- Division of Applied
Life
Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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373
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Abstract
Complex I functions as the initial electron acceptor in aerobic respiratory chains of most organisms. This gigantic redox-driven enzyme employs the energy from quinone reduction to pump protons across its complete approximately 200-Å membrane domain, thermodynamically driving synthesis of ATP. Despite recently resolved structures from several species, the molecular mechanism by which complex I catalyzes this long-range proton-coupled electron transfer process, however, still remains unclear. We perform here large-scale classical and quantum molecular simulations to study the function of the proton pump in complex I from Thermus thermophilus The simulations suggest that proton channels are established at symmetry-related locations in four subunits of the membrane domain. The channels open up by formation of quasi one-dimensional water chains that are sensitive to the protonation states of buried residues at structurally conserved broken helix elements. Our combined data provide mechanistic insight into long-range coupling effects and predictions for site-directed mutagenesis experiments.
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374
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Scialò F, Fernández-Ayala DJ, Sanz A. Role of Mitochondrial Reverse Electron Transport in ROS Signaling: Potential Roles in Health and Disease. Front Physiol 2017; 8:428. [PMID: 28701960 PMCID: PMC5486155 DOI: 10.3389/fphys.2017.00428] [Citation(s) in RCA: 289] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 06/02/2017] [Indexed: 12/20/2022] Open
Abstract
Reactive Oxygen Species (ROS) can cause oxidative damage and have been proposed to be the main cause of aging and age-related diseases including cancer, diabetes and Parkinson's disease. Accordingly, mitochondria from old individuals have higher levels of ROS. However, ROS also participate in cellular signaling, are instrumental for several physiological processes and boosting ROS levels in model organisms extends lifespan. The current consensus is that low levels of ROS are beneficial, facilitating adaptation to stress via signaling, whereas high levels of ROS are deleterious because they trigger oxidative stress. Based on this model the amount of ROS should determine the physiological effect. However, recent data suggests that the site at which ROS are generated is also instrumental in determining effects on cellular homeostasis. The best example of site-specific ROS signaling is reverse electron transport (RET). RET is produced when electrons from ubiquinol are transferred back to respiratory complex I, reducing NAD+ to NADH. This process generates a significant amount of ROS. RET has been shown to be instrumental for the activation of macrophages in response to bacterial infection, re-organization of the electron transport chain in response to changes in energy supply and adaptation of the carotid body to changes in oxygen levels. In Drosophila melanogaster, stimulating RET extends lifespan. Here, we review what is known about RET, as an example of site-specific ROS signaling, and its implications for the field of redox biology.
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Affiliation(s)
- Filippo Scialò
- Institute for Cell and Molecular Biosciences, Newcastle University Institute for Ageing, Newcastle UniversityNewcastle upon Tyne, United Kingdom
| | - Daniel J Fernández-Ayala
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-CSIC and CIBERER-ISCIIISeville, Spain
| | - Alberto Sanz
- Institute for Cell and Molecular Biosciences, Newcastle University Institute for Ageing, Newcastle UniversityNewcastle upon Tyne, United Kingdom
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375
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Papa S, Capitanio G, Papa F. The mechanism of coupling between oxido-reduction and proton translocation in respiratory chain enzymes. Biol Rev Camb Philos Soc 2017. [DOI: 10.1111/brv.12347] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Sergio Papa
- Department of Basic Medical Sciences, Neurosciences and Sense Organs (BMSNSO), Section of Medical Biochemistry; University of Bari ‘Aldo Moro’; Piazza G. Cesare 11 70124 Bari Italy
- Institute of Biomembranes and Bioenergetics; National Research Council at BMSNSO; Piazza G. Cesare 11 70124 Bari Italy
| | - Giuseppe Capitanio
- Department of Basic Medical Sciences, Neurosciences and Sense Organs (BMSNSO), Section of Medical Biochemistry; University of Bari ‘Aldo Moro’; Piazza G. Cesare 11 70124 Bari Italy
| | - Francesco Papa
- Department of Basic Medical Sciences, Neurosciences and Sense Organs (BMSNSO), Section of Medical Biochemistry; University of Bari ‘Aldo Moro’; Piazza G. Cesare 11 70124 Bari Italy
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376
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Abstract
The pace at which cryo-EM is being adopted as a mainstream tool in structural biology has continued unabated over the past year. Initial successes in obtaining near-atomic resolution structures with cryo-EM were enabled to a large extent by advances in microscope and detector technology. Here, we review some of the complementary technical improvements that are helping sustain the cryo-EM revolution. We highlight advances in image processing that permit high resolution structure determination even in the presence of structural and conformational heterogeneity. We also review selected examples where biochemical strategies for membrane protein stabilization facilitate cryo-EM structure determination, and discuss emerging approaches for further improving the preparation of reliable plunge-frozen specimens.
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377
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Abstract
Recent evidence highlights that the cancer cell energy requirements vary greatly from normal cells and that cancer cells exhibit different metabolic phenotypes with variable participation of both glycolysis and oxidative phosphorylation. NADH-ubiquinone oxidoreductase (Complex I) is the largest complex of the mitochondrial electron transport chain and contributes about 40% of the proton motive force required for mitochondrial ATP synthesis. In addition, Complex I plays an essential role in biosynthesis and redox control during proliferation, resistance to cell death, and metastasis of cancer cells. Although knowledge about the structure and assembly of Complex I is increasing, information about the role of Complex I subunits in tumorigenesis is scarce and contradictory. Several small molecule inhibitors of Complex I have been described as selective anticancer agents; however, pharmacologic and genetic interventions on Complex I have also shown pro-tumorigenic actions, involving different cellular signaling. Here, we discuss the role of Complex I in tumorigenesis, focusing on the specific participation of Complex I subunits in proliferation and metastasis of cancer cells.
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Affiliation(s)
- Félix A Urra
- Anatomy and Developmental Biology Program, Institute of Biomedical Sciences, University of Chile, Santiago, Chile.,Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Felipe Muñoz
- Anatomy and Developmental Biology Program, Institute of Biomedical Sciences, University of Chile, Santiago, Chile.,Geroscience Center for Brain Health and Metabolism, Santiago, Chile
| | - Alenka Lovy
- Department of Neuroscience, Center for Neuroscience Research, Tufts School of Medicine, Boston, MA, United States
| | - César Cárdenas
- Anatomy and Developmental Biology Program, Institute of Biomedical Sciences, University of Chile, Santiago, Chile.,Geroscience Center for Brain Health and Metabolism, Santiago, Chile.,The Buck Institute for Research on Aging, Novato, CA, United States.,Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA, United States
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378
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Beutner G, Porter GA. Analyzing Supercomplexes of the Mitochondrial Electron Transport Chain with Native Electrophoresis, In-gel Assays, and Electroelution. J Vis Exp 2017. [PMID: 28605384 DOI: 10.3791/55738] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The mitochondrial electron transport chain (ETC) transduces the energy derived from the breakdown of various fuels into the bioenergetic currency of the cell, ATP. The ETC is composed of 5 massive protein complexes, which also assemble into supercomplexes called respirasomes (C-I, C-III, and C-IV) and synthasomes (C-V) that increase the efficiency of electron transport and ATP production. Various methods have been used for over 50 years to measure ETC function, but these protocols do not provide information on the assembly of individual complexes and supercomplexes. This protocol describes the technique of native gel polyacrylamide gel electrophoresis (PAGE), a method that was modified more than 20 years ago to study ETC complex structure. Native electrophoresis permits the separation of ETC complexes into their active forms, and these complexes can then be studied using immunoblotting, in-gel assays (IGA), and purification by electroelution. By combining the results of native gel PAGE with those of other mitochondrial assays, it is possible to obtain a completer picture of ETC activity, its dynamic assembly and disassembly, and how this regulates mitochondrial structure and function. This work will also discuss limitations of these techniques. In summary, the technique of native PAGE, followed by immunoblotting, IGA, and electroelution, presented below, is a powerful way to investigate the functionality and composition of mitochondrial ETC supercomplexes.
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Affiliation(s)
- Gisela Beutner
- Department of Pediatrics-Division Cardiology, University of Rochester
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379
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Dörner K, Vranas M, Schimpf J, Straub IR, Hoeser J, Friedrich T. Significance of [2Fe-2S] Cluster N1a for Electron Transfer and Assembly of Escherichia coli Respiratory Complex I. Biochemistry 2017; 56:2770-2778. [DOI: 10.1021/acs.biochem.6b01058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Katerina Dörner
- Institut
für Biochemie, Albert-Ludwigs-Universität, Albertstraße 21, 79104 Freiburg, Germany
| | - Marta Vranas
- Spemann
Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University, Freiburg, Germany
| | - Johannes Schimpf
- Institut
für Biochemie, Albert-Ludwigs-Universität, Albertstraße 21, 79104 Freiburg, Germany
| | - Isabella R. Straub
- Institut
für Biochemie, Albert-Ludwigs-Universität, Albertstraße 21, 79104 Freiburg, Germany
| | - Jo Hoeser
- Institut
für Biochemie, Albert-Ludwigs-Universität, Albertstraße 21, 79104 Freiburg, Germany
| | - Thorsten Friedrich
- Spemann
Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University, Freiburg, Germany
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380
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Gao L, González-Rodríguez P, Ortega-Sáenz P, López-Barneo J. Redox signaling in acute oxygen sensing. Redox Biol 2017; 12:908-915. [PMID: 28476010 PMCID: PMC5426049 DOI: 10.1016/j.redox.2017.04.033] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 03/24/2017] [Accepted: 04/24/2017] [Indexed: 11/22/2022] Open
Abstract
Acute oxygen (O2) sensing is essential for individuals to survive under hypoxic conditions. The carotid body (CB) is the main peripheral chemoreceptor, which contains excitable and O2-sensitive glomus cells with O2-regulated ion channels. Upon exposure to acute hypoxia, inhibition of K+ channels is the signal that triggers cell depolarization, transmitter release and activation of sensory fibers that stimulate the brainstem respiratory center to produce hyperventilation. The molecular mechanisms underlying O2 sensing by glomus cells have, however, remained elusive. Here we discuss recent data demonstrating that ablation of mitochondrial Ndufs2 gene selectively abolishes sensitivity of glomus cells to hypoxia, maintaining responsiveness to hypercapnia or hypoglycemia. These data suggest that reactive oxygen species and NADH generated in mitochondrial complex I during hypoxia are signaling molecules that modulate membrane K+ channels. We propose that the structural substrates for acute O2 sensing in CB glomus cells are “O2-sensing microdomains” formed by mitochondria and neighboring K+ channels in the plasma membrane. Acute O2 sensing by peripheral chemoreceptors depends on K+ channels. Mitochondrial complex I function is required for acute O2 sensing. Reactive oxygen species inhibits background K+ channels during acute hypoxia. Pyridine nucleotides may signal voltage-gated K+ channels during acute hypoxia.
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Affiliation(s)
- Lin Gao
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Seville, Spain.
| | - Patricia González-Rodríguez
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Seville, Spain
| | - Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Seville, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain; Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Seville, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Seville, Spain.
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381
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Cai K, Frederick RO, Tonelli M, Markley JL. Mitochondrial Cysteine Desulfurase and ISD11 Coexpressed in Escherichia coli Yield Complex Containing Acyl Carrier Protein. ACS Chem Biol 2017; 12:918-921. [PMID: 28233492 PMCID: PMC5404276 DOI: 10.1021/acschembio.6b01005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
Mitochondrial
cysteine desulfurase is an essential component of
the machinery for iron–sulfur cluster biosynthesis. It has
been known that human cysteine desulfurase that is catalytically active in vitro can be prepared by overexpressing in Escherichia
coli cells two protein components of this system, the cysteine
desulfurase protein NFS1 and the auxiliary protein ISD11. We report
here that this active preparation contains, in addition, the holo-form
of E. coli acyl carrier protein (Acp). We have determined
the stoichiometry of the complex to be [Acp]2:[ISD11]2:[NFS1]2. Acyl carrier protein recently has been
found to be an essential component of the iron–sulfur protein
biosynthesis machinery in mitochondria; thus, because of the activity
of [Acp]2:[ISD11]2:[NFS1]2 in supporting
iron–sulfur cluster assembly in vitro, it
appears that E. coli Acp can substitute for its human
homologue.
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Affiliation(s)
- Kai Cai
- Biochemistry Department, University of Wisconsin—Madison, 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Ronnie O. Frederick
- Biochemistry Department, University of Wisconsin—Madison, 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Marco Tonelli
- Biochemistry Department, University of Wisconsin—Madison, 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - John L. Markley
- Biochemistry Department, University of Wisconsin—Madison, 433 Babcock Drive, Madison, Wisconsin 53706, United States
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382
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Galkin A, Moncada S. Modulation of the conformational state of mitochondrial complex I as a target for therapeutic intervention. Interface Focus 2017; 7:20160104. [PMID: 28382200 DOI: 10.1098/rsfs.2016.0104] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In recent years, there have been significant advances in our understanding of the functions of mitochondrial complex I other than the generation of energy. These include its role in generation of reactive oxygen species, involvement in the hypoxic tissue response and its possible regulation by nitric oxide (NO) metabolites. In this review, we will focus on the hypoxic conformational change of this mitochondrial enzyme, the so-called active/deactive transition. This conformational change is physiological and relevant to the understanding of certain pathological conditions including, in the cardiovascular system, ischaemia/reperfusion (I/R) damage. We will discuss how complex I can be affected by NO metabolites and will outline some potential mitochondria-targeted therapies in I/R damage.
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Affiliation(s)
- Alexander Galkin
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, 401 East 61st Street, 5th floor, New York, NY 10065, USA; Queens University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Salvador Moncada
- Manchester Cancer Research Centre , University of Manchester , Wilmslow Road, Manchester M20 4QL , UK
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383
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Abstract
Respiratory chain dysfunction plays an important role in human disease and aging. It is now well established that the individual respiratory complexes can be organized into supercomplexes, and structures for these macromolecular assemblies, determined by electron cryo-microscopy, have been described recently. Nevertheless, the reason why supercomplexes exist remains an enigma. The widely held view that they enhance catalysis by channeling substrates is challenged by both structural and biophysical information. Here, we evaluate and discuss data and hypotheses on the structures, roles, and assembly of respiratory-chain supercomplexes and propose a future research agenda to address unanswered questions.
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Affiliation(s)
- Dusanka Milenkovic
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Strasse 9b, 50931 Cologne, Germany
| | - James N Blaza
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Strasse 9b, 50931 Cologne, Germany; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden.
| | - Judy Hirst
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.
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384
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Jones AJY, Blaza JN, Varghese F, Hirst J. Respiratory Complex I in Bos taurus and Paracoccus denitrificans Pumps Four Protons across the Membrane for Every NADH Oxidized. J Biol Chem 2017; 292:4987-4995. [PMID: 28174301 PMCID: PMC5377811 DOI: 10.1074/jbc.m116.771899] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/27/2017] [Indexed: 11/22/2022] Open
Abstract
Respiratory complex I couples electron transfer between NADH and ubiquinone to proton translocation across an energy-transducing membrane to support the proton-motive force that drives ATP synthesis. The proton-pumping stoichiometry of complex I (i.e. the number of protons pumped for each two electrons transferred) underpins all mechanistic proposals. However, it remains controversial and has not been determined for any of the bacterial enzymes that are exploited as model systems for the mammalian enzyme. Here, we describe a simple method for determining the proton-pumping stoichiometry of complex I in inverted membrane vesicles under steady-state ADP-phosphorylating conditions. Our method exploits the rate of ATP synthesis, driven by oxidation of NADH or succinate with different sections of the respiratory chain engaged in catalysis as a proxy for the rate of proton translocation and determines the stoichiometry of complex I by reference to the known stoichiometries of complexes III and IV. Using vesicles prepared from mammalian mitochondria (from Bos taurus) and from the bacterium Paracoccus denitrificans, we show that four protons are pumped for every two electrons transferred in both cases. By confirming the four-proton stoichiometry for mammalian complex I and, for the first time, demonstrating the same value for a bacterial complex, we establish the utility of P. denitrificans complex I as a model system for the mammalian enzyme. P. denitrificans is the first system described in which mutagenesis in any complex I core subunit may be combined with quantitative proton-pumping measurements for mechanistic studies.
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Affiliation(s)
- Andrew J Y Jones
- From the Medical Research Council Mitochondrial Biology Unit, Cambridge, CB2 0XY, United Kingdom
| | - James N Blaza
- From the Medical Research Council Mitochondrial Biology Unit, Cambridge, CB2 0XY, United Kingdom
| | - Febin Varghese
- From the Medical Research Council Mitochondrial Biology Unit, Cambridge, CB2 0XY, United Kingdom
| | - Judy Hirst
- From the Medical Research Council Mitochondrial Biology Unit, Cambridge, CB2 0XY, United Kingdom
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385
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Lee SY, Kang MG, Shin S, Kwak C, Kwon T, Seo JK, Kim JS, Rhee HW. Architecture Mapping of the Inner Mitochondrial Membrane Proteome by Chemical Tools in Live Cells. J Am Chem Soc 2017; 139:3651-3662. [DOI: 10.1021/jacs.6b10418] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
| | | | - Sanghee Shin
- Center
for RNA Research, Institute of Basic Science (IBS), Seoul 08826, Korea
- School
of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | | | | | | | - Jong-Seo Kim
- Center
for RNA Research, Institute of Basic Science (IBS), Seoul 08826, Korea
- School
of Biological Sciences, Seoul National University, Seoul 08826, Korea
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386
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Sunnucks P, Morales HE, Lamb AM, Pavlova A, Greening C. Integrative Approaches for Studying Mitochondrial and Nuclear Genome Co-evolution in Oxidative Phosphorylation. Front Genet 2017; 8:25. [PMID: 28316610 PMCID: PMC5334354 DOI: 10.3389/fgene.2017.00025] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 02/17/2017] [Indexed: 01/24/2023] Open
Abstract
In animals, interactions among gene products of mitochondrial and nuclear genomes (mitonuclear interactions) are of profound fitness, evolutionary, and ecological significance. Most fundamentally, the oxidative phosphorylation (OXPHOS) complexes responsible for cellular bioenergetics are formed by the direct interactions of 13 mitochondrial-encoded and ∼80 nuclear-encoded protein subunits in most animals. It is expected that organisms will develop genomic architecture that facilitates co-adaptation of these mitonuclear interactions and enhances biochemical efficiency of OXPHOS complexes. In this perspective, we present principles and approaches to understanding the co-evolution of these interactions, with a novel focus on how genomic architecture might facilitate it. We advocate that recent interdisciplinary advances assist in the consolidation of links between genotype and phenotype. For example, advances in genomics allow us to unravel signatures of selection in mitochondrial and nuclear OXPHOS genes at population-relevant scales, while newly published complete atomic-resolution structures of the OXPHOS machinery enable more robust predictions of how these genes interact epistatically and co-evolutionarily. We use three case studies to show how integrative approaches have improved the understanding of mitonuclear interactions in OXPHOS, namely those driving high-altitude adaptation in bar-headed geese, allopatric population divergence in Tigriopus californicus copepods, and the genome architecture of nuclear genes coding for mitochondrial functions in the eastern yellow robin.
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Affiliation(s)
- Paul Sunnucks
- School of Biological Sciences, Monash University, ClaytonVIC, Australia
| | - Hernán E. Morales
- School of Biological Sciences, Monash University, ClaytonVIC, Australia
- Department of Marine Sciences, University of GothenburgGothenburg, Sweden
| | - Annika M. Lamb
- School of Biological Sciences, Monash University, ClaytonVIC, Australia
| | - Alexandra Pavlova
- School of Biological Sciences, Monash University, ClaytonVIC, Australia
| | - Chris Greening
- School of Biological Sciences, Monash University, ClaytonVIC, Australia
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387
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Giannoccaro MP, La Morgia C, Rizzo G, Carelli V. Mitochondrial DNA and primary mitochondrial dysfunction in Parkinson's disease. Mov Disord 2017; 32:346-363. [PMID: 28251677 DOI: 10.1002/mds.26966] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 01/27/2017] [Accepted: 01/30/2017] [Indexed: 12/15/2022] Open
Abstract
In 1979, it was observed that parkinsonism could be induced by a toxin inhibiting mitochondrial respiratory complex I. This initiated the long-standing hypothesis that mitochondrial dysfunction may play a key role in the pathogenesis of Parkinson's disease (PD). This hypothesis evolved, with accumulating evidence pointing to complex I dysfunction, which could be caused by environmental or genetic factors. Attention was focused on the mitochondrial DNA, considering the occurrence of mutations, polymorphic haplogroup-specific variants, and defective mitochondrial DNA maintenance with the accumulation of multiple deletions and a reduction of copy number. Genetically determined diseases of mitochondrial DNA maintenance frequently manifest with parkinsonism, but the age-related accumulation of somatic mitochondrial DNA errors also represents a major driving mechanism for PD. Recently, the discovery of the genetic cause of rare inherited forms of PD highlighted an extremely complex homeostatic control over mitochondria, involving their dynamic fission/fusion cycle, the balancing of mitobiogenesis and mitophagy, and consequently the quality control surveillance that corrects faulty mitochondrial DNA maintenance. Many genes came into play, including the PINK1/parkin axis, but also OPA1, as pieces of the same puzzle, together with mitochondrial DNA damage, complex I deficiency and increased oxidative stress. The search for answers will drive future research to reach the understanding necessary to provide therapeutic options directed not only at limiting the clinical evolution of symptoms but also finally addressing the pathogenic mechanisms of neurodegeneration in PD. © 2017 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Maria Pia Giannoccaro
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Chiara La Morgia
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Giovanni Rizzo
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
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388
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Bridges HR, Mohammed K, Harbour ME, Hirst J. Subunit NDUFV3 is present in two distinct isoforms in mammalian complex I. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2017; 1858:197-207. [PMID: 27940020 PMCID: PMC5293009 DOI: 10.1016/j.bbabio.2016.12.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 11/29/2016] [Accepted: 12/07/2016] [Indexed: 01/10/2023]
Abstract
Complex I (NADH:ubiquinone oxidoreductase) is the first enzyme of the electron transport chain in mammalian mitochondria. Extensive proteomic and structural analyses of complex I from Bos taurus heart mitochondria have shown it comprises 45 subunits encoded on both the nuclear and mitochondrial genomes; 44 of them are different and one is present in two copies. The bovine heart enzyme has provided a model for studying the composition of complex I in other mammalian species, including humans, but the possibility of additional subunits or isoforms in other species or tissues has not been explored. Here, we describe characterization of the complexes I purified from five rat tissues and from a rat hepatoma cell line. We identify a~50kDa isoform of subunit NDUFV3, for which the canonical isoform is only ~10kDa in size. We combine LC-MS and MALDI-TOF mass spectrometry data from two different purification methods (chromatography and immuno-purification) with information from blue native PAGE analyses to show the long isoform is present in the mature complex, but at substoichiometric levels. It is also present in complex I in cultured human cells. We describe evidence that the long isoform is more abundant in both the mitochondria and purified complexes from brain (relative to in heart, liver, kidney and skeletal muscle) and more abundant still in complex I in cultured cells. We propose that the long 50kDa isoform competes with its canonical 10kDa counterpart for a common binding site on the flavoprotein domain of complex I.
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Affiliation(s)
- Hannah R Bridges
- The Medical Research Council Mitochondrial Biology Unit, Wellcome Trust / MRC Building, Hills Road, Cambridge, CB2 0XY, U. K
| | - Khairunnisa Mohammed
- The Medical Research Council Mitochondrial Biology Unit, Wellcome Trust / MRC Building, Hills Road, Cambridge, CB2 0XY, U. K
| | - Michael E Harbour
- The Medical Research Council Mitochondrial Biology Unit, Wellcome Trust / MRC Building, Hills Road, Cambridge, CB2 0XY, U. K
| | - Judy Hirst
- The Medical Research Council Mitochondrial Biology Unit, Wellcome Trust / MRC Building, Hills Road, Cambridge, CB2 0XY, U. K..
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389
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Krishnathas R, Bonke E, Dröse S, Zickermann V, Nasiri HR. Identification of 4- N-[2-(4-phenoxyphenyl)ethyl]quinazoline-4,6-diamine as a novel, highly potent and specific inhibitor of mitochondrial complex I. MEDCHEMCOMM 2017; 8:657-661. [PMID: 30108783 DOI: 10.1039/c6md00655h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 02/17/2017] [Indexed: 12/21/2022]
Abstract
By probing the quinone substrate binding site of mitochondrial complex I with a focused set of quinazoline-based compounds, we identified substitution patterns as being critical for the observed inhibition. The structure activity relationship study also resulted in the discovery of the quinazoline 4-N-[2-(4-phenoxyphenyl)ethyl]quinazoline-4,6-diamine (EVP4593) as a highly potent inhibitor of the multisubunit membrane protein. EVP4593 specifically and effectively reduces the mitochondrial complex I-dependent respiration with no effect on the respiratory chain complexes II-IV. Similar to established Q-site inhibitors, EVP4593 elicits the release of reactive oxygen species at the flavin site of mitochondrial complex I. Recently, EVP4593 was nominated as a lead compound for the treatment of Huntingtons disease. Our results challenge the postulated primary mode-of-action of EVP4593 as an inhibitor of NF-κB pathway activation and/or store-operated calcium influx.
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Affiliation(s)
- Robin Krishnathas
- Johann Wolfgang Goethe-University Frankfurt , Max-von-Laue-Straße 7 , D-60438 Frankfurt am Main , Germany .
| | - Erik Bonke
- Department of Anaesthesiology , Intensive-Care Medicine and Pain Therapy , University Hospital Frankfurt , 60590 Frankfurt am Main , Germany
| | - Stefan Dröse
- Department of Anaesthesiology , Intensive-Care Medicine and Pain Therapy , University Hospital Frankfurt , 60590 Frankfurt am Main , Germany
| | - Volker Zickermann
- Structural Bioenergetics Group , Institute of Biochemistry II , Medical School , Goethe-University , 60438 Frankfurt am Main , Germany.,Cluster of Excellence Frankfurt "Macromolecular Complexes," , Goethe-University , 60438 Frankfurt am Main , Germany
| | - Hamid R Nasiri
- Johann Wolfgang Goethe-University Frankfurt , Max-von-Laue-Straße 7 , D-60438 Frankfurt am Main , Germany .
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390
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Friederich MW, Erdogan AJ, Coughlin CR, Elos MT, Jiang H, O’Rourke CP, Lovell MA, Wartchow E, Gowan K, Chatfield KC, Chick WS, Spector EB, Van Hove JL, Riemer J. Mutations in the accessory subunit NDUFB10 result in isolated complex I deficiency and illustrate the critical role of intermembrane space import for complex I holoenzyme assembly. Hum Mol Genet 2017; 26:702-716. [PMID: 28040730 PMCID: PMC6251674 DOI: 10.1093/hmg/ddw431] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/27/2016] [Accepted: 12/16/2016] [Indexed: 12/17/2022] Open
Abstract
An infant presented with fatal infantile lactic acidosis and cardiomyopathy, and was found to have profoundly decreased activity of respiratory chain complex I in muscle, heart and liver. Exome sequencing revealed compound heterozygous mutations in NDUFB10, which encodes an accessory subunit located within the PD part of complex I. One mutation resulted in a premature stop codon and absent protein, while the second mutation replaced the highly conserved cysteine 107 with a serine residue. Protein expression of NDUFB10 was decreased in muscle and heart, and less so in the liver and fibroblasts, resulting in the perturbed assembly of the holoenzyme at the 830 kDa stage. NDUFB10 was identified together with three other complex I subunits as a substrate of the intermembrane space oxidoreductase CHCHD4 (also known as Mia40). We found that during its mitochondrial import and maturation NDUFB10 transiently interacts with CHCHD4 and acquires disulfide bonds. The mutation of cysteine residue 107 in NDUFB10 impaired oxidation and efficient mitochondrial accumulation of the protein and resulted in degradation of non-imported precursors. Our findings indicate that mutations in NDUFB10 are a novel cause of complex I deficiency associated with a late stage assembly defect and emphasize the role of intermembrane space proteins for the efficient assembly of complex I.
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Affiliation(s)
- Marisa W. Friederich
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Alican J. Erdogan
- Department of Chemistry, Institute of Biochemistry, University of Cologne, Cologne, Germany
| | - Curtis R. Coughlin
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Mihret T. Elos
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Hua Jiang
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Courtney P. O’Rourke
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Mark A. Lovell
- Department of Pathology, University of Colorado, Aurora, CO, USA
- Department of Pathology, Children’s Hospital of Colorado, Aurora, CO, USA
| | - Eric Wartchow
- Department of Pathology, University of Colorado, Aurora, CO, USA
- Department of Pathology, Children’s Hospital of Colorado, Aurora, CO, USA
| | - Katherine Gowan
- Department of Biochemistry and Molecular Genetics, University of Colorado, Aurora, CO, USA
| | - Kathryn C. Chatfield
- Department of Pediatrics, Section of Cardiology, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Wallace S. Chick
- Department of Cell and Developmental Biology, University of Colorado, Aurora, CO, USA
| | - Elaine B. Spector
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Johan L.K. Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Jan Riemer
- Department of Chemistry, Institute of Biochemistry, University of Cologne, Cologne, Germany
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391
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Mitochondrial protein interactome elucidated by chemical cross-linking mass spectrometry. Proc Natl Acad Sci U S A 2017; 114:1732-1737. [PMID: 28130547 PMCID: PMC5321032 DOI: 10.1073/pnas.1617220114] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Mitochondrial protein interactions and complexes facilitate mitochondrial function. These complexes range from simple dimers to the respirasome supercomplex consisting of oxidative phosphorylation complexes I, III, and IV. To improve understanding of mitochondrial function, we used chemical cross-linking mass spectrometry to identify 2,427 cross-linked peptide pairs from 327 mitochondrial proteins in whole, respiring murine mitochondria. In situ interactions were observed in proteins throughout the electron transport chain membrane complexes, ATP synthase, and the mitochondrial contact site and cristae organizing system (MICOS) complex. Cross-linked sites showed excellent agreement with empirical protein structures and delivered complementary constraints for in silico protein docking. These data established direct physical evidence of the assembly of the complex I-III respirasome and enabled prediction of in situ interfacial regions of the complexes. Finally, we established a database and tools to harness the cross-linked interactions we observed as molecular probes, allowing quantification of conformation-dependent protein interfaces and dynamic protein complex assembly.
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392
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Efremov RG, Gatsogiannis C, Raunser S. Lipid Nanodiscs as a Tool for High-Resolution Structure Determination of Membrane Proteins by Single-Particle Cryo-EM. Methods Enzymol 2017; 594:1-30. [DOI: 10.1016/bs.mie.2017.05.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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393
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Dibley MG, Ryan MT, Stroud DA. A novel isoform of the human mitochondrial complex I subunit NDUFV3. FEBS Lett 2016; 591:109-117. [PMID: 27987311 DOI: 10.1002/1873-3468.12527] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/09/2016] [Accepted: 12/09/2016] [Indexed: 12/30/2022]
Abstract
Human mitochondrial complex I is the first enzyme of the mitochondrial respiratory chain. Complex I is composed of 45 subunits, seven encoded by mitochondrial DNA, while the remainder are encoded by nuclear DNA. All nuclear-encoded subunits are thought to be expressed as a single isoform. Here we reveal subunit NDUFV3 to be present in both the canonical 10 kDa and a novel 50 kDa isoform, generated through alternative splicing. Both isoforms assemble into complex I and their levels vary in different tissues. While the 50 kDa isoform appears to be dominant in HEK293T cells, we find either isoform alone is sufficient for assembly of mature complex I. NDUFV3 represents the first known complex I subunit present in two functional isoforms.
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Affiliation(s)
- Marris G Dibley
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia
| | - Michael T Ryan
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia
| | - David A Stroud
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia
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394
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Gerber S, Ding MG, Gérard X, Zwicker K, Zanlonghi X, Rio M, Serre V, Hanein S, Munnich A, Rotig A, Bianchi L, Amati-Bonneau P, Elpeleg O, Kaplan J, Brandt U, Rozet JM. Compound heterozygosity for severe and hypomorphic NDUFS2 mutations cause non-syndromic LHON-like optic neuropathy. J Med Genet 2016; 54:346-356. [PMID: 28031252 DOI: 10.1136/jmedgenet-2016-104212] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 11/29/2016] [Accepted: 12/01/2016] [Indexed: 11/03/2022]
Abstract
BACKGROUND Non-syndromic hereditary optic neuropathy (HON) has been ascribed to mutations in mitochondrial fusion/fission dynamics genes, nuclear and mitochondrial DNA-encoded respiratory enzyme genes or nuclear genes of poorly known mitochondrial function. However, the disease causing gene remains unknown in many families. The objective of the present study was to identify the molecular cause of non-syndromic LHON-like disease in siblings born to non-consanguineous parents of French origin. METHODS We used a combination of genetic analysis (gene mapping and whole-exome sequencing) in a multiplex family of non-syndromic HON and of functional analyses in patient-derived cultured skin fibroblasts and the yeast Yarrowia lipolytica. RESULTS We identified compound heterozygote NDUFS2 disease-causing mutations (p.Tyr53Cys; p.Tyr308Cys). Studies using patient-derived cultured skin fibroblasts revealed mildly decreased NDUFS2 and complex I abundance but apparently normal respiratory chain activity. In the yeast Y. lipolytica ortholog NUCM, the mutations resulted in absence of complex I and moderate reduction in nicotinamide adenine dinucleotide-ubiquinone oxidoreductase activity, respectively. CONCLUSIONS Biallelism for NDUFS2 mutations causing severe complex I deficiency has been previously reported to cause Leigh syndrome with optic neuropathy. Our results are consistent with the view that compound heterozygosity for severe and hypomorphic NDUFS2 mutations can cause non-syndromic HON. This observation suggests a direct correlation between the severity of NDUFS2 mutations and that of the disease and further support that there exist a genetic overlap between non-syndromic and syndromic HON due to defective mitochondrial function.
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Affiliation(s)
- Sylvie Gerber
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine, Paris Descartes University, Paris, France
| | - Martina G Ding
- Molecular Bioenergetics Group, Goethe-University Medical School, Frankfurt am Main, Germany
| | - Xavier Gérard
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine, Paris Descartes University, Paris, France
| | - Klaus Zwicker
- Institute of Biochemistry I, Goethe-University Medical School, Frankfurt am Main, Germany
| | | | - Marlène Rio
- Department of Genetics, Necker Hospital, Paris, France
| | - Valérie Serre
- UMR7592 CNRS, Jacques Monod Institute, Paris Diderot University, Paris, France.,Laboratory of Genetics in Mitochondrial Diseases, INSERM UMR1163, Institute of Genetic Diseases, Imagine, Paris Descartes University, Paris, France
| | - Sylvain Hanein
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine, Paris Descartes University, Paris, France
| | | | - Agnès Rotig
- Laboratory of Genetics in Mitochondrial Diseases, INSERM UMR1163, Institute of Genetic Diseases, Imagine, Paris Descartes University, Paris, France
| | - Lucas Bianchi
- Laboratory of Genetics in Mitochondrial Diseases, INSERM UMR1163, Institute of Genetic Diseases, Imagine, Paris Descartes University, Paris, France
| | - Patrizia Amati-Bonneau
- Department of Biochemistry and Genetics, UMR CNRS 6214-INSERM U1083, CHU Angers, Angers, France
| | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Josseline Kaplan
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine, Paris Descartes University, Paris, France
| | - Ulrich Brandt
- Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Center, Nijmegen, The Netherlands.,Cluster of Excellence Frankfurt Macromolecular Complexes, Goethe-University, Frankfurt am Main, Germany
| | - Jean-Michel Rozet
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetic Diseases, Imagine, Paris Descartes University, Paris, France
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395
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Guerrero-Castillo S, Cabrera-Orefice A, Huynen MA, Arnold S. Identification and evolutionary analysis of tissue-specific isoforms of mitochondrial complex I subunit NDUFV3. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1858:208-217. [PMID: 27988283 DOI: 10.1016/j.bbabio.2016.12.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 11/22/2016] [Accepted: 12/13/2016] [Indexed: 11/24/2022]
Abstract
Mitochondrial complex I is the largest respiratory chain complex. Despite the enormous progress made studying its structure and function in recent years, potential regulatory roles of its accessory subunits remained largely unresolved. Complex I gene NDUFV3, which occurs in metazoa, contains an extra exon that is only present in vertebrates and thereby evolutionary even younger than the rest of the gene. Alternative splicing of this extra exon gives rise to a short NDUFV3-S and a long NDUFV3-L protein isoform. Complexome profiling revealed that the two NDUFV3 isoforms are constituents of the multi-subunit complex I. Further mass spectrometric analyses of complex I from different murine and bovine tissues showed a tissue-specific expression pattern of NDUFV3-S and NDUFV3-L. Hence, NDUFV3-S was identified as the only isoform in heart and skeletal muscle, whereas in liver, brain, and lung NDUFV3-L was expressed as the dominant isoform, together with NDUFV3-S present in all tissues analyzed. Thus, we identified NDUFV3 as the first out of 30 accessory subunits of complex I present in vertebrate- and tissue-specific isoforms. Interestingly, the tissue-specific expression pattern of NDUFV3-S and NDUFV3-L isoforms was paralleled by changes in kinetic parameters, especially the substrate affinity of complex I. This may indicate a regulatory role of the NDUFV3 isoforms in different vertebrate tissues.
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Affiliation(s)
- Sergio Guerrero-Castillo
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Alfredo Cabrera-Orefice
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Martijn A Huynen
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands; Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Susanne Arnold
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
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396
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Structure of Mammalian Respiratory Supercomplex I 1 III 2 IV 1. Cell 2016; 167:1598-1609.e10. [DOI: 10.1016/j.cell.2016.11.012] [Citation(s) in RCA: 251] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 10/27/2016] [Accepted: 11/03/2016] [Indexed: 01/14/2023]
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397
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Abstract
Structure determination by cryo-electron microscopy has approached atomic resolution and helped solve structures of large membrane-protein complexes that resisted crystallography. The 4.0 Å cryo-EM structure of one of the most intricate enzyme systems, the respirasome, in the mitochondrial inner membrane is reported in this issue of Cell.
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Affiliation(s)
- Andrew Melber
- University of Utah Health Sciences Center, Salt Lake City UT 84132, USA
| | - Dennis R Winge
- University of Utah Health Sciences Center, Salt Lake City UT 84132, USA.
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398
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Garvin MR, Templin WD, Gharrett AJ, DeCovich N, Kondzela CM, Guyon JR, McPhee MV. Potentially adaptive mitochondrial haplotypes as a tool to identify divergent nuclear loci. Methods Ecol Evol 2016. [DOI: 10.1111/2041-210x.12698] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael R. Garvin
- Oregon State University Ringgold Standard Institution ‐ Integrative Biology 3029 Cordley Hall, 2701 SW Campus Way Corvallis OR 97331‐4501 USA
| | - William D. Templin
- Alaska Department of Fish and Game Division of Commercial Fisheries 333 Raspberry Road Anchorage AK 99518 USA
| | - Anthony J. Gharrett
- University of Alaska Fairbanks College Fisheries and Ocean Sciences Juneau AK 99821 USA
| | - Nick DeCovich
- Alaska Department of Fish and Game Division of Commercial Fisheries 333 Raspberry Road Anchorage AK 99518 USA
| | - Christine M. Kondzela
- Auke Bay Laboratories Alaska Fisheries Science Center National Oceanic and Atmospheric Administration National Marine Fisheries Service 17109 Point Lena Loop Road Juneau AK 99801 USA
| | - Jeffrey R. Guyon
- Auke Bay Laboratories Alaska Fisheries Science Center National Oceanic and Atmospheric Administration National Marine Fisheries Service 17109 Point Lena Loop Road Juneau AK 99801 USA
| | - Megan V. McPhee
- University of Alaska Fairbanks College Fisheries and Ocean Sciences Juneau AK 99821 USA
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399
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Kahlhöfer F, Kmita K, Wittig I, Zwicker K, Zickermann V. Accessory subunit NUYM (NDUFS4) is required for stability of the electron input module and activity of mitochondrial complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1858:175-181. [PMID: 27871794 DOI: 10.1016/j.bbabio.2016.11.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 11/15/2016] [Accepted: 11/17/2016] [Indexed: 11/18/2022]
Abstract
Mitochondrial complex I is an intricate 1MDa membrane protein complex with a central role in aerobic energy metabolism. The minimal form of complex I consists of fourteen central subunits that are conserved from bacteria to man. In addition, eukaryotic complex I comprises some 30 accessory subunits of largely unknown function. The gene for the accessory NDUFS4 subunit of human complex I is a hot spot for fatal pathogenic mutations in humans. We have deleted the gene for the orthologous NUYM subunit in the aerobic yeast Yarrowia lipolytica, an established model system to study eukaryotic complex I and complex I linked diseases. We observed assembly of complex I which lacked only subunit NUYM and retained weak interaction with assembly factor N7BML (human NDUFAF2). Absence of NUYM caused distortion of iron sulfur clusters of the electron input domain leading to decreased complex I activity and increased release of reactive oxygen species. We conclude that NUYM has an important stabilizing function for the electron input module of complex I and is essential for proper complex I function.
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Affiliation(s)
- Flora Kahlhöfer
- Structural Bioenergetics Group, Institute of Biochemistry II, Medical School, Goethe-University Frankfurt am Main, Germany
| | - Katarzyna Kmita
- Structural Bioenergetics Group, Institute of Biochemistry II, Medical School, Goethe-University Frankfurt am Main, Germany
| | - Ilka Wittig
- Functional Proteomics, Institute of Biochemistry I, Medical School, Goethe-University Frankfurt am Main, Germany; Cluster of Excellence Frankfurt "Macromolecular Complexes", Goethe-University Frankfurt am Main, Germany
| | - Klaus Zwicker
- Institute of Biochemistry I, Medical School, Goethe University Frankfurt am Main, Germany
| | - Volker Zickermann
- Structural Bioenergetics Group, Institute of Biochemistry II, Medical School, Goethe-University Frankfurt am Main, Germany; Cluster of Excellence Frankfurt "Macromolecular Complexes", Goethe-University Frankfurt am Main, Germany.
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400
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Sousa JS, Mills DJ, Vonck J, Kühlbrandt W. Functional asymmetry and electron flow in the bovine respirasome. eLife 2016; 5. [PMID: 27830641 PMCID: PMC5117854 DOI: 10.7554/elife.21290] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 11/03/2016] [Indexed: 01/11/2023] Open
Abstract
Respirasomes are macromolecular assemblies of the respiratory chain complexes I, III and IV in the inner mitochondrial membrane. We determined the structure of supercomplex I1III2IV1 from bovine heart mitochondria by cryo-EM at 9 Å resolution. Most protein-protein contacts between complex I, III and IV in the membrane are mediated by supernumerary subunits. Of the two Rieske iron-sulfur cluster domains in the complex III dimer, one is resolved, indicating that this domain is immobile and unable to transfer electrons. The central position of the active complex III monomer between complex I and IV in the respirasome is optimal for accepting reduced quinone from complex I over a short diffusion distance of 11 nm, and delivering reduced cytochrome c to complex IV. The functional asymmetry of complex III provides strong evidence for directed electron flow from complex I to complex IV through the active complex III monomer in the mammalian supercomplex. DOI:http://dx.doi.org/10.7554/eLife.21290.001
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Affiliation(s)
- Joana S Sousa
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Deryck J Mills
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
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